Genera : 40 +/-
Links to genus directories:
Distribution: Cosmopolitan, with the greatest diversity in the arctic, boreal and montane regions of the Northern Hemisphere.
Economic Uses: Important as cultivated garden ornamentals, especially in rock gardens or in gardens composed of native woodland plants.
Defining Features of Interest: The family is debated regarding the features delimiting it from other families. It has been widely imterpreted by various botanists.
fossils from Eocene deposits.